A mobile and smart device such as a smartphone is not simply a communication device but may act as a smart personal digital assistant (PDA). Recent generations of smartphones include a number of sensors such as accelerometers, gyroscopes, compass, pressure sensor, light sensor, temperature and humidity sensors. Some sensors are used to help improve user-input interfacing, some are used for navigation, and others are used to increase people's awareness about the surrounding environment such as temperature and humidity
Ambient air temperature is one of the most interesting and basic environmental parameters that people want to know. Temperature perception of humans is usually not accurate. Temperature perception varies with seasons and is affected by a number of factors such as illness, wind, and dynamic changes in temperature. In many cases, smartphone users want to measure ambient temperature accurately, for example to check if an outdoor temperature is close to the freezing point to determine the danger of ice forming, whether a bedroom temperature is within the comfortable zone for an infant, or sharing locations on social media with local ambient temperature automatically attached.